Radar wave absorbing rubber material and preparation method thereof

Abstract

This invention discloses a radar-absorbing rubber material and its preparation method. The radar-absorbing rubber material comprises the following raw materials in parts by weight: 10-30 parts of polymer rubber, 50-75 parts of absorbent, 1-3 parts of coupling agent, 1-2 parts of coumarone, 1-2 parts of zinc stearate, 1-3 parts of zinc methacrylate, 1-3 parts of microcrystalline wax, 1-2 parts of dioctyl sebate, 1-2 parts of dioctyl adipate, 2-6 parts of antioxidant, 1-2 parts of waterproofing agent, 1-2 parts of UV stabilizer, 2-4 parts of vulcanizing agent, 1-2 parts of anti-scorching agent, 1-2 parts of accelerator, and 0.5-1 parts of anti-mildew agent; wherein the absorbent is a flake-shaped alloy powder treated with a coupling agent. The radar absorbing rubber material provided by this invention has good broadband absorption performance and corrosion resistance. After 2400 hours of neutral salt spray, the absorption performance of the material decreases by no more than 10%, and there are no rust or cracks on the surface. It effectively solves the problems of poor corrosion resistance, narrow absorption bandwidth, decreased absorption performance and rust in marine environments of current radar absorbing rubber materials.

Description

Technical Field

[0001] This invention relates to the field of radar absorbing materials technology, specifically to a radar absorbing rubber material and its preparation method. Background Technology

[0002] With the rapid development of radar absorbing materials, they have been applied to various fields of weaponry and equipment, such as ground equipment, aircraft, naval equipment, and civilian electronic equipment. Especially in naval equipment, my country's ships and submarines have an increasing demand for radar absorbing materials. However, conventional absorbing materials are mainly used in ground and air equipment. Various absorbing materials prepared with carbonyl iron powder as the absorbing agent cannot meet the requirements for long-term use in the high humidity, high heat, and strong corrosion of the marine environment. They often suffer from problems such as rust, delamination, and peeling, which seriously reduces the absorbing performance and greatly reduces the stealth performance of the equipment.

[0003] Currently, microwave absorbing materials used in marine environments mainly consist of carbonyl iron as the primary absorber and carbon-based absorbers. Carbonyl iron-based materials offer advantages such as a wide absorption bandwidth and strong absorption performance, but they are highly susceptible to corrosion in marine environments, significantly reducing their absorption capacity. Carbon-based microwave absorbing materials mainly include carbon fibers, carbon nanotubes, graphene, and carbon black. These materials offer advantages such as good corrosion resistance and light weight, but their disadvantages include poor absorption performance, making it difficult to meet stealth requirements and severely limiting their practical applications. Summary of the Invention

[0004] The main objective of this invention is to propose a radar absorbing rubber material and its preparation method, aiming to provide a long-lasting, corrosion-resistant, broadband radar absorbing material.

[0005] To achieve the above objectives, the present invention proposes a radar-absorbing rubber material, wherein the radar-absorbing rubber material comprises the following raw materials in parts by weight:

[0006] The composition includes 10-30 parts of polymer rubber, 50-75 parts of absorbent, 1-3 parts of coupling agent, 1-2 parts of coumarone, 1-2 parts of zinc stearate, 1-3 parts of zinc methacrylate, 1-3 parts of microcrystalline wax, 1-2 parts of dioctyl sebate, 1-2 parts of dioctyl adipate, 2-6 parts of antioxidant, 1-2 parts of waterproofing agent, 1-2 parts of UV protectant, 2-4 parts of vulcanizing agent, 1-2 parts of anti-scorching agent, 1-2 parts of accelerator, and 0.5-1 parts of mildew inhibitor; wherein the absorbent is a flake-shaped alloy powder treated with the coupling agent.

[0007] Optionally, the polymeric rubber includes any one of nitrile rubber, ethylene propylene rubber, and polyurethane rubber.

[0008] Optionally, the alloy powder includes any one or any two of the following: iron-silicon-aluminum-chromium, iron-silicon-aluminum-nickel, and iron-silicon-aluminum-molybdenum.

[0009] Optionally, the particle size of the absorbent is 5 to 60 μm.

[0010] Optionally, the absorbent has a real dielectric constant of 30-35 and an imaginary dielectric constant of 1.3-3.5 at 2 GHz, a real permeability of 6-15 and an imaginary permeability of 2-5.

[0011] Optionally, the antioxidant includes antioxidant RD and antioxidant MB; and / or,

[0012] The coupling agent includes coupling agent KH580; and / or,

[0013] The UV-blocking agent includes the UV-blocking agent DBH; and / or,

[0014] The vulcanizing agent includes vulcanizing agent DCP; and / or,

[0015] The scorching inhibitor includes N-cyclohexylthiophthalimide; and / or...

[0016] The accelerator includes accelerator TMTD.

[0017] To achieve the above objectives, the present invention also proposes a method for preparing the radar-absorbing rubber material as described above, comprising the following steps:

[0018] Step S10: The alloy powder is processed into flakes by ball milling to obtain a flake-shaped alloy powder absorbent.

[0019] Step S20: The polymer rubber is mixed with coumarone, zinc stearate, zinc methacrylate, microcrystalline wax, dioctyl sebate, dioctyl adipate, antioxidant, waterproofing agent, UV stabilizer, vulcanizing agent, scorching inhibitor, accelerator, and mildew inhibitor for the first time. After mixing, the mixture is allowed to stand to obtain the initial mixed rubber compound.

[0020] Step S30: The compound rubber and the flake-shaped alloy powder absorbent are mixed for the second time. After the mixing is completed, the mixture is allowed to stand to obtain the compound rubber material.

[0021] Step S40: The mixed rubber compound is calendered into sheets and then placed in a mold for vulcanization to obtain radar absorbing rubber material.

[0022] Optionally, the step of preparing a flake-shaped alloy powder absorbent by ball milling includes:

[0023] The alloy powder and coupling agent were placed in a ball mill jar, which was filled with nitrogen. The jar was then ball milled for 3 to 5 hours at a frequency of 32 to 48 Hz. After the ball milling was completed, the mixture was cooled to room temperature and sieved to obtain a flake-shaped alloy powder absorbent.

[0024] The grinding jar is equipped with grinding media, which includes a first stainless steel ball with a diameter of 6 mm and a second stainless steel ball with a diameter of 8 mm. The mass ratio of the first stainless steel ball to the second stainless steel ball is 5:3.

[0025] Optionally, the mixing time for the first mixing step is 1–3 hours, and the mixture is allowed to stand for 10–24 hours after mixing; and / or,

[0026] The second mixing method is open mixing, with a roller spacing of 1-2 mm and a mixing time of 1-2 hours. After mixing, the mixture is left to stand for 10-24 hours.

[0027] Optionally, in the step of calendering the compounded rubber into sheets and then vulcanizing them in a mold to obtain radar-absorbing rubber material:

[0028] During the calendering process, the calendering temperature is 30–40°C, the roll gap is 0.8–1.5 mm, and the resulting green sheet has a width of 330–650 mm and a thickness of 1–2 mm; and / or,

[0029] During the vulcanization process, the vulcanization temperature is 110–190℃, the vulcanization pressure is 5–12MPa, and the vulcanization time is 30–50min.

[0030] The technical solution provided by this invention uses polymer rubber, a sheet-like alloy powder absorber treated with a coupling agent, zinc methacrylate, a waterproofing agent, and other additives as raw materials to prepare a radar absorbing rubber material. After the alloy powder is treated with a coupling agent, a protective film of the coupling agent can be formed on its surface. On the one hand, this can reduce the dielectric constant of the absorber, and on the other hand, it can improve the affinity between the absorber and the polymer rubber, thereby improving their bonding. By adding zinc methacrylate and a waterproofing agent, seawater erosion can be effectively prevented, and the density, water resistance, and mechanical strength of the radar absorbing rubber material can be improved. It is better suited for marine environments, has good broadband radar absorption performance and corrosion resistance, and also has good low-temperature resistance and UV resistance. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic flowchart of an embodiment of the preparation method of the radar absorbing rubber material provided by the present invention.

[0033] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Currently, microwave absorbing materials used in marine environments mainly consist of carbonyl iron as the primary absorber and carbon-based absorbers. Carbonyl iron-based materials offer advantages such as a wide absorption bandwidth and strong absorption performance, but they are highly susceptible to corrosion in marine environments, significantly reducing their absorption capacity. Carbon-based microwave absorbing materials mainly include carbon fibers, carbon nanotubes, graphene, and carbon black. These materials offer advantages such as good corrosion resistance and light weight, but their disadvantages include poor absorption performance, making it difficult to meet stealth requirements and severely limiting their practical applications.

[0036] In view of this, the present invention proposes a radar absorbing rubber material, the main raw materials of which include polymer rubber, absorbent, and rubber additives, which can improve the corrosion resistance of the radar absorbing rubber material and solve the problem that the current radar absorbing materials are not corrosion resistant and their radar absorption performance is significantly reduced in marine environments. Specifically, in the present invention, the radar absorbing rubber material includes the following raw materials in parts by weight: 10-30 parts polymer rubber, 50-75 parts absorbent, 1-3 parts coupling agent, 1-2 parts coumarone, 1-2 parts zinc stearate, 1-3 parts zinc methacrylate, 1-3 parts microcrystalline wax, 1-2 parts dioctyl sebate, 1-2 parts dioctyl adipate, 2-6 parts antioxidant, 1-2 parts waterproofing agent, 1-2 parts UV stabilizer, 2-4 parts vulcanizing agent, 1-2 parts anti-scorching agent, 1-2 parts accelerator, and 0.5-1 parts anti-mildew agent; wherein, the absorbent is a flake-shaped alloy powder treated with the coupling agent.

[0037] The technical solution provided by this invention uses polymer rubber, a sheet-like alloy powder absorber treated with a coupling agent, zinc methacrylate, a waterproofing agent, and other additives as raw materials to prepare a radar absorbing rubber material. After the alloy powder is treated with a coupling agent, a protective film of the coupling agent can be formed on its surface. On the one hand, this can reduce the dielectric constant of the absorber, and on the other hand, it can improve the affinity between the absorber and the polymer rubber, thus improving their bonding. By adding zinc methacrylate and a waterproofing agent, seawater erosion can be effectively prevented, and the density, water resistance, and mechanical strength of the radar absorbing rubber material can be improved. It is better suited for marine environments and has good broadband absorption performance and corrosion resistance. After 2400 hours of neutral salt spray, the absorption performance of the material decreases by no more than 10%, and there are no rust or cracks on the surface. This effectively solves the problems of poor corrosion resistance, narrow absorption bandwidth, decreased absorption performance in marine environments, and rust in current radar absorbing rubber materials. In addition, it also has good low-temperature resistance and UV resistance.

[0038] In some embodiments of the present invention, the polymeric rubber includes, but is not limited to, any one of nitrile rubber, ethylene propylene rubber, and polyurethane rubber.

[0039] In some embodiments of the present invention, the alloy powder includes any one or any two of iron-silicon-aluminum-chromium, iron-silicon-aluminum-nickel, and iron-silicon-aluminum-molybdenum. When the alloy powder includes any two of iron-silicon-aluminum-chromium, iron-silicon-aluminum-nickel, and iron-silicon-aluminum-molybdenum, the specific mass ratio of the two alloy powders is not limited and all fall within the protection scope of the present invention.

[0040] In some embodiments of the present invention, the particle size of the absorbent is 5 to 60 μm.

[0041] In this invention, the absorber is a sheet-like alloy powder treated with a coupling agent, preferably KH580. This allows the absorber to possess specific electromagnetic parameters, enabling the adjustment of the absorption bandwidth and intensity of the radar absorbing rubber material by regulating these parameters, thus achieving adjustable absorption performance. Absorbers with different electromagnetic parameters exhibit different absorption effects in the 1–18 GHz range. The absorbing rubber material can achieve -8 dB in the 1–8 GHz range and -4 dB in the 8–18 GHz range. Specifically, in some embodiments of this invention, the absorber has a real dielectric constant of 30–35, an imaginary dielectric constant of 1.3–3.5, a real permeability of 6–15, and an imaginary permeability of 2–5 at 2 GHz. Furthermore, the absorption performance can also be adjusted by regulating the thickness of the radar absorbing rubber material, for example, the absorption effects of radar absorbing rubber with thicknesses of 1 mm and 2 mm, as further explained in the specific embodiments below.

[0042] In some embodiments of the present invention, the antioxidant includes antioxidant RD and antioxidant MB. Further, the antioxidant RD is present in 1 to 3 parts by mass, and the antioxidant MB is present in 1 to 3 parts by mass.

[0043] In some embodiments of the present invention, the UV stabilizer includes the UV stabilizer DBH.

[0044] In some embodiments of the present invention, the vulcanizing agent includes the vulcanizing agent DCP.

[0045] In some embodiments of the present invention, the scorching inhibitor comprises N-cyclohexylthiophthalimide.

[0046] In some embodiments of the present invention, the accelerator includes the accelerator TMTD.

[0047] Based on the radar absorbing rubber material provided by the present invention, the present invention also proposes a method for preparing the radar absorbing rubber material as described above. Figure 1 The image shows an embodiment of the preparation method of the radar absorbing rubber material provided by the present invention, which specifically includes the following steps:

[0048] Step S10: The alloy powder is processed into flakes by ball milling to obtain a flake-shaped alloy powder absorbent.

[0049] Step S20: The polymer rubber is mixed with coumarone, zinc stearate, zinc methacrylate, microcrystalline wax, dioctyl sebate, dioctyl adipate, antioxidant, waterproofing agent, UV stabilizer, vulcanizing agent, scorching inhibitor, accelerator, and mildew inhibitor for the first time. After mixing, the mixture is allowed to stand to obtain the initial mixed rubber compound.

[0050] Step S30: The compound rubber and the flake-shaped alloy powder absorbent are mixed for the second time. After the mixing is completed, the mixture is allowed to stand to obtain the compound rubber material.

[0051] Step S40: The mixed rubber compound is calendered into sheets and then placed in a mold for vulcanization to obtain radar absorbing rubber material.

[0052] First, the alloy powder is processed using a ball milling process to obtain flake-shaped alloy powder as an absorbent. This alloy powder is treated with a coupling agent, forming a protective film on its surface with specific electromagnetic parameters. The polymer rubber and various additives are then first mixed, and after uniform mixing, allowed to stand to obtain a preliminary mixed rubber compound. Next, the preliminary mixed rubber compound and the alloy powder absorbent are mixed a second time, and after uniform mixing, allowed to stand to obtain a final mixed rubber compound. Finally, the final mixed rubber compound is calendered into sheets in a calender, and then vulcanized in a mold to obtain the radar absorbing rubber material. The radar absorbing rubber material preparation method provided by this invention is simple and practical, requires few equipment, and is conducive to mass production. The obtained radar absorbing rubber material has excellent corrosion resistance, wide-band absorption performance, and mechanical properties. Furthermore, its absorption performance is easily adjustable; after 2400 hours of neutral salt spray treatment, the absorption performance of the material decreases by no more than 10%, and there are no signs of rust or cracking on the surface.

[0053] When the alloy powder is processed by ball milling, absorbents with specific electromagnetic parameters can be prepared by adjusting the process parameters and the amount of coupling agent added. In some embodiments of the present invention, step S10 includes: placing the alloy powder and coupling agent in a ball milling jar, filling the ball milling jar with nitrogen gas, and then ball milling at a ball milling frequency of 32-48 Hz for 3-5 hours. After ball milling, the mixture is cooled to room temperature and sieved to obtain a flake-like alloy powder absorbent. The ball milling jar contains milling media, which includes a first stainless steel ball with a diameter of 6 mm and a second stainless steel ball with a diameter of 8 mm, wherein the mass ratio of the first stainless steel ball to the second stainless steel ball is 5:3.

[0054] Specifically, a 20L planetary ball mill is used for ball milling. Each single milling jar is equipped with 5kg of stainless steel balls with a diameter of 6mm and 3kg of stainless steel balls with a diameter of 8mm. 1-3kg of alloy powder and 0.05-0.1kg of coupling agent are added to each milling jar. The milling jar is filled with nitrogen for protection and cooling. Ball milling is carried out at a frequency of 32-48Hz for 3-5 hours. After milling, the powder is cooled to room temperature and sieved to obtain a flake-like alloy powder absorbent. After the above ball milling treatment, a coupling agent protective film is formed on the surface of the alloy powder. This film reduces the dielectric constant of the absorbent and improves the affinity and bonding between the absorbent and the polymer rubber, thereby enhancing the mechanical strength, corrosion resistance, and radar absorption performance of the radar absorbing rubber material.

[0055] In some embodiments of the present invention, the first mixing method can be open milling or internal milling, and the mixing time for the first mixing is 1 to 3 hours, followed by standing for 10 to 24 hours. Further, in some embodiments of the present invention, the second mixing method is open milling, with a roller spacing of 1 to 2 mm, a mixing time of 1 to 2 hours, and a standing time of 10 to 24 hours after mixing.

[0056] In the preparation method of radar absorbing rubber material provided by the present invention, the absorption bandwidth and intensity of the radar absorbing rubber material can be adjusted by adjusting the electromagnetic parameters of the absorber and the thickness of the material to meet the application requirements of the radar absorbing rubber material. Specifically, in some embodiments of the present invention, the parameters in the calendering process are set as follows: calendering temperature is 30-40℃, roll spacing is 0.8-1.5mm, and the width of the calendered green sheet is 330-650mm and the thickness is 1-2mm.

[0057] In addition, in some embodiments of the present invention, the parameters in the vulcanization process are set as follows: vulcanization temperature is 110-190°C, vulcanization pressure is 5-12 MPa, and vulcanization time is 30-50 min.

[0058] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0059] Example 1

[0060] (1) Weigh the following raw materials according to the following weight proportions: 30 parts of nitrile rubber, 50 parts of alloy powder (iron, silicon, aluminum and chromium with a particle size of 5-10 μm), 1 part of coupling agent KH580, 2 parts of coumarone, 2 parts of zinc stearate, 1 part of zinc methacrylate, 1 part of microcrystalline wax, 1 part of dioctyl sebacate, 1 part of dioctyl adipate, 1 part of antioxidant RD, 1 part of antioxidant MB, 1 part of waterproofing agent, 1 part of UV protectant DBH, 4 parts of vulcanizing agent DCP, 1 part of anti-scorching agent N-cyclohexylthiophthalimide, 1 part of accelerator TMTD, and 1 part of antifungal agent;

[0061] (2) A 20L planetary ball mill was used for ball milling. Each single ball mill jar was equipped with 5kg of stainless steel balls with a diameter of 6mm and 3kg of stainless steel balls with a diameter of 8mm. 1kg of alloy powder and 0.05kg of coupling agent were added to each ball mill jar. The ball mill jar was filled with nitrogen for protection and cooling. The ball milling was carried out for 3 hours at a ball milling frequency of 32Hz. After the ball milling was completed, the mixture was cooled to room temperature and sieved to obtain a flake-shaped alloy powder absorbent. Its dielectric constant at 2GHz had a real part of 30, an imaginary part of 1.3, a real part of 6, and an imaginary part of 2.

[0062] (3) Mix the nitrile rubber and all the additives by open milling for 1 hour. After mixing evenly, let stand for 10 hours to obtain the initial mixture.

[0063] (4) The initial compound and the alloy powder absorbent were mixed by open milling. The roller gap was 1 mm and the open milling time was 1 h. After the mixture was uniformly mixed, it was left to stand for 10 h to obtain the compound.

[0064] (5) The prepared compound rubber is placed in a calender and calendered into sheets. The calender roller temperature is 30°C, the roller spacing is 0.8mm and 1.5mm, the width is 330mm and 650mm, and the thickness of the calendered green sheets is 1mm and 2mm, respectively. The green sheets are then placed in a mold for vulcanization. The vulcanization temperature is 110°C, the vulcanization pressure is 5MPa, and the vulcanization time is 30min. After vulcanization, the sheets are cut to obtain radar absorbing rubber material.

[0065] The obtained 1mm and 2mm thick microwave absorbing rubber materials exhibit excellent corrosion resistance, mechanical properties, and microwave absorption performance. After 2400 hours of neutral salt spray testing, the material surface showed no rust or cracking, and the tensile strength reached 10MPa with an elongation at break of 320%. Specifically, the 1mm thick microwave absorbing rubber material showed absorption performance of less than -1.5dB in the 1–4GHz range, less than -2.5dB in the 4–8GHz range, and less than -5dB in the 8–18GHz range. After the salt spray test, the absorption performance was less than -1.8dB in the 1–4GHz range, less than -2.0dB in the 4–8GHz range, and less than -4.8dB in the 8–18GHz range. The 2mm thick microwave absorbing rubber material exhibits absorption performance of less than -1.8dB in the 1–4GHz range, less than -7.6dB in the 4–8GHz range, and less than -5dB in the 8–18GHz range. After salt spray testing, the absorption performance is less than -2.0dB in the 4–8GHz range and less than -4.8dB in the 8–18GHz range.

[0066] Example 2

[0067] (1) Weigh the following raw materials according to the following weight proportions: 20 parts of ethylene propylene rubber, 50 parts of alloy powder (iron, silicon, aluminum and nickel with a particle size of 10-20 μm), 2 parts of coupling agent KH580, 1.5 parts of coumarone, 1.5 parts of zinc stearate, 2 parts of zinc methacrylate, 1 part of microcrystalline wax, 1.5 parts of dioctyl sebacate, 1.5 parts of dioctyl adipate, 3 parts of antioxidant RD, 2 parts of antioxidant MB, 1.5 parts of waterproofing agent, 1.5 parts of UV protectant DBH, 3 parts of vulcanizing agent DCP, 1.5 parts of anti-scorching agent N-cyclohexylthiophthalimide, 1.5 parts of accelerator TMTD, and 0.5 parts of mildew inhibitor;

[0068] (2) A 20L planetary ball mill was used for ball milling. Each single ball mill jar was equipped with 5kg of stainless steel balls with a diameter of 6mm and 3kg of stainless steel balls with a diameter of 8mm. 1kg of alloy powder and 0.05kg of coupling agent were added to each ball mill jar. The ball mill jar was filled with nitrogen for protection and cooling. The ball milling was carried out for 4 hours at a ball milling frequency of 35Hz. After the ball milling was completed, the mixture was cooled to room temperature and sieved to obtain a flake-shaped alloy powder absorbent. Its dielectric constant at 2GHz has a real part of 31, an imaginary part of 2, a real part of 8, and an imaginary part of 3.

[0069] (3) Mix the ethylene propylene rubber and all additives by internal mixing. The mixing time is 1.5h. After mixing evenly, let it stand for 10h to obtain the initial mixture.

[0070] (4) The initial compound and the alloy powder absorbent were mixed by open milling. The roller gap of the open mill was 1.5 mm and the open milling time was 2 h. After the mixture was uniformly mixed, it was left to stand for 15 h to obtain the compound.

[0071] (5) The prepared compound rubber is placed in a calender and calendered into sheets. The calender roll temperature is 40℃, the roll gap is 0.8mm and 1.5mm, the width is 330mm and 650mm, and the thickness of the calendered green sheets is 1mm and 2mm, respectively. The green sheets are then placed in a mold for vulcanization. The vulcanization temperature is 130℃, the vulcanization pressure is 12MPa, and the vulcanization time is 40min. After vulcanization, the sheets are cut to obtain radar absorbing rubber material.

[0072] The obtained 1mm and 2mm thick microwave absorbing rubber materials exhibit excellent corrosion resistance, mechanical properties, and microwave absorption performance. After 2400 hours of neutral salt spray testing, the material surface showed no rust or cracking, with a tensile strength of 12MPa and an elongation at break of 260%. Specifically, the 1mm thick microwave absorbing rubber material showed absorption performance of less than -1.8dB in the 1–4GHz range, less than -3.0dB in the 4–8GHz range, and less than -5.2dB in the 8–18GHz range. After the salt spray test, the absorption performance remained less than -2.0dB in the 1–4GHz range, less than -3.2dB in the 4–8GHz range, and less than -5.0dB in the 8–18GHz range. The 2mm thick microwave-absorbing rubber material exhibits absorption performance of less than -4.5dB in the 1–4GHz range, less than -9.7dB in the 4–8GHz range, and less than -6.2dB in the 8–18GHz range. After salt spray testing, the absorption performance remains less than -4.9dB in the 1–4GHz range, less than -10.2dB in the 4–8GHz range, and less than -5.8dB in the 8–18GHz range.

[0073] Example 3

[0074] (1) Weigh the following raw materials according to the following weight proportions: 10 parts polyurethane rubber, 70 parts alloy powder (iron, silicon, aluminum and molybdenum with a particle size of 20-30μm), 2 parts coupling agent KH580, 2 parts coumarone, 2 parts zinc stearate, 2 parts zinc methacrylate, 1 part microcrystalline wax, 2 parts dioctyl sebate, 2 parts dioctyl adipate, 3 parts antioxidant RD, 2 parts antioxidant MB, 2 parts waterproofing agent, 1 part UV stabilizer DBH, 4 parts vulcanizing agent DCP, 2 parts anti-scorching agent N-cyclohexylthiophthalimide, 2 parts accelerator TMTD, and 1 part mildew inhibitor;

[0075] (2) A 20L planetary ball mill was used for ball milling. Each single ball mill jar was equipped with 5kg of stainless steel balls with a diameter of 6mm and 3kg of stainless steel balls with a diameter of 8mm. 1kg of alloy powder and 0.05kg of coupling agent were added to each ball mill jar. The ball mill jar was filled with nitrogen for protection and cooling. The ball milling was carried out for 3 hours at a ball milling frequency of 40Hz. After the ball milling was completed, the mixture was cooled to room temperature and sieved to obtain a flake-shaped alloy powder absorbent. Its dielectric constant at 2GHz had a real part of 32, an imaginary part of 2.5, a real part of 12, and an imaginary part of 2.5.

[0076] (3) Mix the nitrile rubber and all the additives by open milling for 2 hours. After mixing evenly, let stand for 10 hours to obtain the initial mixture.

[0077] (4) The initial compound and the alloy powder absorbent were mixed by open milling. The roller gap of the open mill was 1.5 mm and the open milling time was 2 h. After the mixture was uniformly mixed, it was left to stand for 15 h to obtain the compound.

[0078] (5) The prepared compound rubber is placed in a calender and calendered into sheets. The calender roll temperature is 35℃, the roll gap is 0.8mm and 1.5mm, the width is 330mm and 650mm, and the thickness of the calendered green sheets is 1mm and 2mm, respectively. The green sheets are then placed in a mold for vulcanization. The vulcanization temperature is 160℃, the vulcanization pressure is 12MPa, and the vulcanization time is 50min. After vulcanization, the sheets are cut to obtain radar absorbing rubber material.

[0079] The obtained 1mm and 2mm thick microwave absorbing rubber materials exhibit excellent corrosion resistance, mechanical properties, and microwave absorption performance. After 2400 hours of neutral salt spray testing, the material surface showed no rust or cracking, and the tensile strength reached 14MPa with an elongation at break of 120%. Specifically, the 1mm thick microwave absorbing rubber material showed absorption performance of less than -1.5dB in the 1–4GHz range, less than -2.6dB in the 4–8GHz range, and less than -4.9dB in the 8–18GHz range. After the salt spray test, the absorption performance remained less than -1.7dB in the 1–4GHz range, less than -2.9dB in the 4–8GHz range, and less than -4.7dB in the 8–18GHz range. The 2mm thick absorbing rubber material exhibits absorption performance of less than -4.3dB in the 1–4GHz range, less than -9.4dB in the 4–8GHz range, and less than -6.8dB in the 8–18GHz range. After salt spray testing, the absorption performance remains less than -4.6dB in the 1–4GHz range, less than -10.1dB in the 4–8GHz range, and less than -6.4dB in the 8–18GHz range.

[0080] Example 4

[0081] (1) Weigh the following raw materials according to the following weight proportions: 10 parts of nitrile rubber, 54 parts of alloy powder (iron, silicon, aluminum and chromium with a particle size of 30-40μm), 3 parts of coupling agent KH580, 2 parts of coumarone, 2 parts of zinc stearate, 3 parts of zinc methacrylate, 3 parts of microcrystalline wax, 2 parts of dioctyl sebacate, 2 parts of dioctyl adipate, 3 parts of antioxidant RD, 3 parts of antioxidant MB, 2 parts of waterproofing agent, 2 parts of UV protectant DBH, 4 parts of vulcanizing agent DCP, 2 parts of anti-scorching agent N-cyclohexylthiophthalimide, 2 parts of accelerator TMTD, and 1 part of antifungal agent;

[0082] (2) A 20L planetary ball mill was used for ball milling. Each single ball mill jar was equipped with 5kg of stainless steel balls with a diameter of 6mm and 3kg of stainless steel balls with a diameter of 8mm. 3kg of alloy powder and 0.1kg of coupling agent were added to each ball mill jar. The ball mill jar was filled with nitrogen for protection and cooling. The ball milling was carried out for 5 hours at a ball milling frequency of 48Hz. After the ball milling was completed, the mixture was cooled to room temperature and sieved to obtain a flake-shaped alloy powder absorbent. Its dielectric constant at 2GHz had a real part of 33, an imaginary part of 3, a real part of 14, and an imaginary part of 3.5.

[0083] (3) Mix the nitrile rubber and all the additives by open milling for 3 hours. After mixing evenly, let stand for 24 hours to obtain the initial mixture.

[0084] (4) The initial compound and the alloy powder absorbent were mixed by open milling. The roller gap of the open mill was 2 mm and the open milling time was 2 h. After the mixture was uniformly mixed, it was left to stand for 24 h to obtain the compound.

[0085] (5) The prepared compound rubber is placed in a calender and calendered into sheets. The calender roller temperature is 30°C, the roller spacing is 0.8mm and 1.5mm, the width is 330mm and 650mm, and the thickness of the calendered green sheets is 1mm and 2mm, respectively. The green sheets are then placed in a mold for vulcanization. The vulcanization temperature is 190°C, the vulcanization pressure is 12MPa, and the vulcanization time is 50min. After vulcanization, the sheets are cut to obtain radar absorbing rubber material.

[0086] The obtained 1mm and 2mm thick microwave absorbing rubber materials exhibit excellent corrosion resistance, mechanical properties, and microwave absorption performance. After 2400 hours of neutral salt spray testing, the material surface showed no rust or cracking, and the tensile strength reached 15MPa with an elongation at break of 109%. Specifically, the 1mm thick microwave absorbing rubber material showed absorption performance of less than -3.6dB in the 1–4GHz range, less than -5.3dB in the 4–8GHz range, and less than -3.1dB in the 8–18GHz range. After the salt spray test, the absorption performance was less than -4.2dB in the 1–4GHz range, less than -6.1dB in the 4–8GHz range, and less than -2.9dB in the 8–18GHz range. The 2mm thick microwave-absorbing rubber material exhibits absorption performance of less than -6.7dB in the 1–4GHz range, less than -10.7dB in the 4–8GHz range, and less than -5.4dB in the 8–18GHz range. After salt spray testing, the absorption performance remains less than -7.1dB in the 1–4GHz range, less than -10.8dB in the 4–8GHz range, and less than -5.1dB in the 8–18GHz range.

[0087] Example 5

[0088] (1) Weigh the following raw materials according to the following weight proportions: 10 parts of ethylene propylene rubber, 65 parts of alloy powder (iron, silicon, aluminum and nickel with a particle size of 15-30μm), 3 parts of coupling agent KH580, 2 parts of coumarone, 1 part of zinc stearate, 1 part of zinc methacrylate, 2 parts of microcrystalline wax, 2 parts of dioctyl sebacate, 2 parts of dioctyl adipate, 2 parts of antioxidant RD, 1 part of antioxidant MB, 2 parts of waterproofing agent, 1 part of UV protectant DBH, 2 parts of vulcanizing agent DCP, 2 parts of anti-scorching agent N-cyclohexylthiophthalimide, 1 part of accelerator TMTD, and 1 part of antifungal agent;

[0089] (2) A 20L planetary ball mill was used for ball milling. Each single ball mill jar was equipped with 5kg of stainless steel balls with a diameter of 6mm and 3kg of stainless steel balls with a diameter of 8mm. 3kg of alloy powder and 0.1kg of coupling agent were added to each ball mill jar. The ball mill jar was filled with nitrogen for protection and cooling. The ball milling was carried out for 5 hours at a ball milling frequency of 42Hz. After the ball milling was completed, the mixture was cooled to room temperature and sieved to obtain a flake-shaped alloy powder absorbent. Its dielectric constant at 2GHz had a real part of 34, an imaginary part of 1.5, a real part of 10, and an imaginary part of 4.

[0090] (3) Mix the ethylene propylene rubber and all additives by open milling for 2 hours. After mixing evenly, let stand for 24 hours to obtain the initial mixture.

[0091] (4) The initial compound and the alloy powder absorbent were mixed by open milling. The roller gap was 1 mm and the open milling time was 2 h. After the mixture was uniformly mixed, it was left to stand for 24 h to obtain the compound.

[0092] (5) The prepared compound rubber is placed in a calender and calendered into sheets. The calender roller temperature is 30°C, the roller spacing is 0.8mm and 1.5mm, the width is 330mm and 650mm, and the thickness of the calendered green sheets is 1mm and 2mm, respectively. The green sheets are then placed in a mold for vulcanization. The vulcanization temperature is 160°C, the vulcanization pressure is 8MPa, and the vulcanization time is 40min. After vulcanization, the sheets are cut to obtain radar absorbing rubber material.

[0093] The obtained 1mm and 2mm thick microwave absorbing rubber materials exhibit excellent corrosion resistance, mechanical properties, and microwave absorption performance. After 2400 hours of neutral salt spray testing, the material surface showed no rust or cracking, and the tensile strength reached 13MPa with an elongation at break of 142%. Specifically, the 1mm thick microwave absorbing rubber material showed absorption performance of less than -3.1dB in the 1–4GHz range, less than -4.9dB in the 4–8GHz range, and less than -3.7dB in the 8–18GHz range. After the salt spray test, the absorption performance remained less than -3.9dB in the 1–4GHz range, less than -5.7dB in the 4–8GHz range, and less than -3.6dB in the 8–18GHz range. The 2mm thick microwave-absorbing rubber material exhibits absorption performance of less than -6.1dB in the 1–4GHz range, less than -9.8dB in the 4–8GHz range, and less than -5.0dB in the 8–18GHz range. After salt spray testing, the absorption performance remains less than -6.6dB in the 1–4GHz range, less than -10.1dB in the 4–8GHz range, and less than -4.7dB in the 8–18GHz range.

[0094] Example 6

[0095] (1) Weigh the following raw materials according to the following weight proportions: 10 parts of ethylene propylene rubber, 75 parts of alloy powder (iron, silicon, aluminum and molybdenum with a particle size of 50-60μm), 2 parts of coupling agent KH580, 1 part of coumarone, 1 part of zinc stearate, 1 part of zinc methacrylate, 1.5 parts of microcrystalline wax, 1 part of dioctyl sebacate, 1 part of dioctyl adipate, 1 part of antioxidant RD, 1 part of antioxidant MB, 1 part of waterproofing agent, 1 part of UV protectant DBH, 2 parts of vulcanizing agent DCP, 1 part of anti-scorching agent N-cyclohexylthiophthalimide, 1 part of accelerator TMTD, and 1 part of antifungal agent;

[0096] (2) A 20L planetary ball mill was used for ball milling. Each single ball mill jar was equipped with 5kg of stainless steel balls with a diameter of 6mm and 3kg of stainless steel balls with a diameter of 8mm. 2kg of alloy powder and 0.08kg of coupling agent were added to each ball mill jar. The ball mill jar was filled with nitrogen for protection and cooling. The ball milling was carried out for 5 hours at a ball milling frequency of 42Hz. After the ball milling was completed, the mixture was cooled to room temperature and sieved to obtain a flake-shaped alloy powder absorbent. Its dielectric constant at 2GHz had a real part of 35, an imaginary part of 3.5, a real part of 15, and an imaginary part of 5.

[0097] (3) Mix the ethylene propylene rubber and all additives by open milling for 2 hours. After mixing evenly, let stand for 24 hours to obtain the initial mixture.

[0098] (4) The initial compound and the alloy powder absorbent were mixed by open milling. The roller gap was 1 mm and the open milling time was 2 h. After the mixture was uniformly mixed, it was left to stand for 24 h to obtain the compound.

[0099] (5) The prepared compound rubber is placed in a calender and calendered into sheets. The calender roller temperature is 30°C, the roller spacing is 0.8mm and 1.5mm, the width is 330mm and 650mm, and the thickness of the calendered green sheets is 1mm and 2mm, respectively. The green sheets are then placed in a mold for vulcanization. The vulcanization temperature is 160°C, the vulcanization pressure is 8MPa, and the vulcanization time is 40min. After vulcanization, the sheets are cut to obtain radar absorbing rubber material.

[0100] The obtained 1mm and 2mm thick microwave absorbing rubber materials exhibit excellent corrosion resistance, mechanical properties, and microwave absorption performance. After 2400 hours of neutral salt spray testing, the material surface showed no rust or cracking, and the tensile strength reached 15MPa with an elongation at break of 97%. Specifically, the 1mm thick microwave absorbing rubber material showed absorption performance of less than -2.3dB in the 1–4GHz range, less than -3.4dB in the 4–8GHz range, and less than -4.2dB in the 8–18GHz range. After the salt spray test, the absorption performance remained less than -2.5dB in the 1–4GHz range, less than -3.6dB in the 4–8GHz range, and less than -4.0dB in the 8–18GHz range. The 2mm thick microwave-absorbing rubber material exhibits absorption performance of less than -4.8dB in the 1–4GHz range, less than -9.6dB in the 4–8GHz range, and less than -6.5dB in the 8–18GHz range. After salt spray testing, the absorption performance remains less than -5.1dB in the 1–4GHz range, less than -10.2dB in the 4–8GHz range, and less than -6.1dB in the 8–18GHz range.

[0101] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A radar absorbing rubber material for use in a marine environment, characterized in that, The radar-absorbing rubber material comprises the following raw materials in parts by weight: The composition includes 10-30 parts of polymer rubber, 50-75 parts of absorbent, 1-3 parts of coupling agent, 1-2 parts of coumarone, 1-2 parts of zinc stearate, 1-3 parts of zinc methacrylate, 1-3 parts of microcrystalline wax, 1-2 parts of dioctyl sebacate, 1-2 parts of dioctyl adipate, 2-6 parts of antioxidant, 1-2 parts of waterproofing agent, 1-2 parts of UV protectant, 2-4 parts of vulcanizing agent, 1-2 parts of anti-scorching agent, 1-2 parts of accelerator, and 0.5-1 parts of mildew inhibitor; wherein the absorbent is a flake-shaped alloy powder treated with the coupling agent. The preparation method of the absorbent is as follows: alloy powder and coupling agent are placed in a ball mill jar, the ball mill jar is filled with nitrogen gas, and then ball milling is carried out for 3 to 5 hours at a ball milling frequency of 32 to 48 Hz. After ball milling, the mixture is cooled to room temperature and sieved to obtain a flake-shaped alloy powder absorbent; the coupling agent includes coupling agent KH580.

2. The radar wave absorbing rubber material of claim 1, wherein, The polymeric rubber includes any one of nitrile rubber, ethylene propylene rubber, and polyurethane rubber.

3. The radar wave absorbing rubber material of claim 1, wherein, The alloy powder includes any one or any two of the following: iron-silicon-aluminum-chromium, iron-silicon-aluminum-nickel, and iron-silicon-aluminum-molybdenum.

4. The radar wave absorbing rubber material of claim 1, wherein, The absorbent has a particle size of 5~60μm.

5. The radar-absorbing rubber material of claim 1, wherein, The absorbent has a real dielectric constant of 30-35 and an imaginary dielectric constant of 1.3-3.5 at 2 GHz, a real permeability of 6-15 and an imaginary permeability of 2-5.

6. The radar-absorbing rubber material of claim 1, wherein, The antioxidant includes antioxidant RD and antioxidant MB; and / or, The UV-blocking agent includes the UV-blocking agent DBH; and / or, The vulcanizing agent includes vulcanizing agent DCP; and / or, The scorching inhibitor includes N-cyclohexylthiophthalimide; and / or... The accelerator includes accelerator TMTD.

7. A method of producing a radar-absorbing rubber material as claimed in any one of claims 1 to 6, characterized in that, Includes the following steps: The alloy powder absorbent was prepared by ball milling to form flakes. The polymer rubber is mixed with coumarone, zinc stearate, zinc methacrylate, microcrystalline wax, dioctyl sebacate, dioctyl adipate, antioxidant, waterproofing agent, UV stabilizer, vulcanizing agent, anti-scorching agent, accelerator, and mildew inhibitor for the first time. After mixing, the mixture is allowed to stand to obtain the initial mixed rubber compound. The compounded rubber is mixed with the flake-shaped alloy powder absorbent for a second time. After mixing, it is allowed to stand to obtain the compounded rubber material. The compounded rubber is calendered into sheets and then placed in a mold for vulcanization to obtain radar absorbing rubber material. The steps of preparing a flake-shaped alloy powder absorbent by ball milling include: The alloy powder and coupling agent are placed in a ball mill jar, which is then filled with nitrogen. The jar is then ball-milled for 3 to 5 hours at a frequency of 32 to 48 Hz. After the ball milling is completed, the mixture is cooled to room temperature and sieved to obtain a flake-like alloy powder absorbent.

8. The method of claim 7, wherein the radar absorbing rubber material is prepared by mixing the conductive filler and the rubber material in a ratio of 1 : 1 to 1 :

10. The grinding jar is equipped with grinding media, which includes a first stainless steel ball with a diameter of 6 mm and a second stainless steel ball with a diameter of 8 mm. The mass ratio of the first stainless steel ball to the second stainless steel ball is 5:

3.

9. The method for preparing the radar-absorbing rubber material as described in claim 7, characterized in that, The first mixing time is 1-3 hours, and after mixing, it is allowed to stand for 10-24 hours; and / or, The second mixing method is open mixing, with a roller spacing of 1~2mm and a mixing time of 1~2h. After mixing, the mixture is left to stand for 10~24h.

10. The method of claim 7, wherein the radar absorbing rubber material is prepared by mixing the conductive filler, the rubber, and the filler in a predetermined ratio. In the step of calendering the compounded rubber into sheets and then vulcanizing them in a mold to obtain radar-absorbing rubber material: During the calendering process, the calendering temperature is 30~40℃, the roll gap is 0.8~1.5mm, and the width of the resulting green sheet is 330~650mm and the thickness is 1~2mm; and / or, During the vulcanization process, the vulcanization temperature is 110~190℃, the vulcanization pressure is 5~12MPa, and the vulcanization time is 30~50min.

Images